Objectives:

To understand the prognosis of endometrial carcinomas and determine their treatment, it is becoming increasingly important to evaluate microsatellite instability (MSI) in endometrial carcinomas and to understand the molecular profile of the tumors. So, in our study, we aimed to determine morphological parameters in patients whose MSI status was investigated immunohistochemically and molecularly in the last two years.

Materials and Methods:

Forty-three patients with endometrial carcinoma, whose microsatellite stability was investigated, were included in the study. Patient age, tumor size and tumor localization, type of material sent and resection material, TNM stage, immunohistochemical staining results and sequencing analysis results, if performed, were obtained from pathology reports and recorded. The H&E stained glasses of the patients were removed from the archive and reevaluated retrospectively. The presence of intratumoral and peritumoral inflammatory cell infiltration, lymphovascular and perineural invasion were examined and recorded.

Results:

Peritumoral and intratumoral inflammatory cell response was found to be mild (+1) in all MSS cases. In the MSI group, the peritumoral inflammatory response was mild (+1) in 5 (28%) tumors, moderate (+2) in 11 (61%) tumors, and severe (+3) in 2 (11%) tumors. Intratumoral inflammation was mild (+1) in 3 (17%) tumors, moderate (+2) in 8 (44%) tumors, and severe (+3) in 7 (39%) tumors. There was a statistically significant difference between the two groups in terms of both peritumoral and intratumoral inflammation (p<0.05 and p<0.001).

Conclusion:

In the MSI group, both intratumoral and peritumoral inflammatory cell densities were found to be higher than in the MSS group, similar to the literature (p<0.001 and p<0.05, respectively). Many studies in the literature have shown that d-MMR or MSI-H group tumors respond much better to PD-1 inhibition treatments. This creates a treatment choice for this group of tumors, which are known to have a worse prognosis than MSS and d-MMR group tumors.

Keywords: Endometrial Carcinoma, Microsatellite Instability, MSI, MSS